I've created non-self moderated topics before where I needed to
add a local rule to keep the thread clean. I reported a comment which was against the rule I set and it was deleted.
I have seen couple to threads where thread creator put a P.S type sentence where they ask some users not to reply on that thread & they point that as local rule of that thread.
I've also seen topics like that but the posts of those users the OP do not want weren't deleted. I guess local rule to ban certain users isn't acceptable.